Andrée Ehresmann (1935-2026)
Dear Colleagues, With great sadness, we inform you of the passing of Andrée Ehresmann (née Bastiani) on Friday, August 21, 2026, at her home in Amiens. Andrée Ehresmann played a major role in the category theory community for over sixty years. Born in Nice in 1935, she went as a young woman to Paris to study mathematics and Latin. She completed her doctoral thesis, and later her thèse d'État, in functional analysis, under the supervision of Gustave Choquet. From 1967, she was maître de conférences, and then professor, at the Université de Picardie in Amiens. It was Choquet who, already during her doctoral studies, encouraged her to take up category theory in the form that Charles Ehresmann was developing at that time. She later met Charles Ehresmann, who became her husband, and with whom she collaborated intensively until his death in 1979. Together they established the French school in category theory in Amiens, which became a vibrant research center, known internationally. From 1970 onwards, she was the driving force behind the Cahiers de Topologie et Géométrie Différentielle Catégoriques, which she directed until her passing. Andrée Ehresmann worked in various areas of category theory and pioneered the applications of categorical methods to the modeling of living and cognitive systems, mainly in collaboration with Jean-Paul Vanbremeersch. Her fundamental scientific contributions have been presented in an invited talk by René Guitart at the Séminaire Itinérant des Catégories held in Louvain-la-Neuve to celebrate her 90th birthday (https://www-lmpa.univ-littoral.fr/~sic/wordpress/?page_id=1609). The slides of René's talk are available here: https://www-lmpa.univ-littoral.fr/~sic/Louvain2025/Guitart.pdf On that occasion, she herself participated remotely and presented a talk, in French, about her scientific career: https://www-lmpa.univ-littoral.fr/~sic/Louvain2025/Ehresmann.pdf In the final months of her life, Andrée Ehresmann's health declined rapidly. Those who knew her personally appreciated her vision, leadership, generosity, and constant support of younger researchers. With her passing, the category theory community loses a prominent mathematician and a uniquely dedicated figure who contributed greatly to a historic era of French mathematics. Best regards, Isar Stubbe, Marino Gran, and René Guitart.
I am so very sad to hear of the passing of Andrée Ehresmann. She was a role model for so many of us, and for me she was also a personal friend and one of my Ada Lovelace heroines. I wrote about Andrée as part of my Ada Lovelace Day reflections, thinking about the women mathematicians who have inspired me and helped shape our community: https://logic-forall.blogspot.com/2023/12/ada-lovelace-day-in-december.html I will remember her with enormous affection and gratitude. My deepest condolences to her family, friends, and all those who were fortunate enough to know and work with her. Valeria On Sun, Aug 23, 2026 at 3:22 AM Isar Stubbe via Categories < categories-list@categories.org.au> wrote:
Dear Colleagues,
With great sadness, we inform you of the passing of Andrée Ehresmann (née Bastiani) on Friday, August 21, 2026, at her home in Amiens.
Andrée Ehresmann played a major role in the category theory community for over sixty years.
Born in Nice in 1935, she went as a young woman to Paris to study mathematics and Latin. She completed her doctoral thesis, and later her thèse d'État, in functional analysis, under the supervision of Gustave Choquet. From 1967, she was maître de conférences, and then professor, at the Université de Picardie in Amiens. It was Choquet who, already during her doctoral studies, encouraged her to take up category theory in the form that Charles Ehresmann was developing at that time. She later met Charles Ehresmann, who became her husband, and with whom she collaborated intensively until his death in 1979. Together they established the French school in category theory in Amiens, which became a vibrant research center, known internationally. From 1970 onwards, she was the driving force behind the Cahiers de Topologie et Géométrie Différentielle Catégoriques, which she directed until her passing.
Andrée Ehresmann worked in various areas of category theory and pioneered the applications of categorical methods to the modeling of living and cognitive systems, mainly in collaboration with Jean-Paul Vanbremeersch. Her fundamental scientific contributions have been presented in an invited talk by René Guitart at the Séminaire Itinérant des Catégories held in Louvain-la-Neuve to celebrate her 90th birthday ( https://www-lmpa.univ-littoral.fr/~sic/wordpress/?page_id=1609). The slides of René's talk are available here:
https://www-lmpa.univ-littoral.fr/~sic/Louvain2025/Guitart.pdf
On that occasion, she herself participated remotely and presented a talk, in French, about her scientific career:
https://www-lmpa.univ-littoral.fr/~sic/Louvain2025/Ehresmann.pdf
In the final months of her life, Andrée Ehresmann's health declined rapidly. Those who knew her personally appreciated her vision, leadership, generosity, and constant support of younger researchers. With her passing, the category theory community loses a prominent mathematician and a uniquely dedicated figure who contributed greatly to a historic era of French mathematics.
Best regards,
Isar Stubbe, Marino Gran, and René Guitart.
_______________________________________________ Categories mailing list -- categories-list@categories.org.au To unsubscribe send an email to categories-list-leave@categories.org.au
Dear everyone, Being a nobody in the field and having never met her, hope this message is not disrespectful in that sense. But she is one of my absolute top top inspirations. Reading the subject line made my body shake, what a loss! My heart felt condolences to everyone and deep respect to madame Andrée Ehresmann, what a grandmaster. I never even communicated with her but found her work extremely inspiring and it has always been a dream of mine to organize a workshop with her like we did near Berlin with amongst others David Spivak. The image on her website displaying the map of extremely broad knowledge, one can only imagine what could have come out of that... https://web.archive.org/web/20260503141522/https://mes-ehres.fr/indexAE.htm Life is so beautiful yet so short, Wish you all well On Sun, Aug 23, 2026 at 9:14 PM Valeria de Paiva via Categories < categories-list@categories.org.au> wrote:
I am so very sad to hear of the passing of Andrée Ehresmann. She was a role model for so many of us, and for me she was also a personal friend and one of my Ada Lovelace heroines.
I wrote about Andrée as part of my Ada Lovelace Day reflections, thinking about the women mathematicians who have inspired me and helped shape our community: https://logic-forall.blogspot.com/2023/12/ada-lovelace-day-in-december.html
I will remember her with enormous affection and gratitude. My deepest condolences to her family, friends, and all those who were fortunate enough to know and work with her. Valeria
On Sun, Aug 23, 2026 at 3:22 AM Isar Stubbe via Categories < categories-list@categories.org.au> wrote:
Dear Colleagues,
With great sadness, we inform you of the passing of Andrée Ehresmann (née Bastiani) on Friday, August 21, 2026, at her home in Amiens.
Andrée Ehresmann played a major role in the category theory community for over sixty years.
Born in Nice in 1935, she went as a young woman to Paris to study mathematics and Latin. She completed her doctoral thesis, and later her thèse d'État, in functional analysis, under the supervision of Gustave Choquet. From 1967, she was maître de conférences, and then professor, at the Université de Picardie in Amiens. It was Choquet who, already during her doctoral studies, encouraged her to take up category theory in the form that Charles Ehresmann was developing at that time. She later met Charles Ehresmann, who became her husband, and with whom she collaborated intensively until his death in 1979. Together they established the French school in category theory in Amiens, which became a vibrant research center, known internationally. From 1970 onwards, she was the driving force behind the Cahiers de Topologie et Géométrie Différentielle Catégoriques, which she directed until her passing.
Andrée Ehresmann worked in various areas of category theory and pioneered the applications of categorical methods to the modeling of living and cognitive systems, mainly in collaboration with Jean-Paul Vanbremeersch. Her fundamental scientific contributions have been presented in an invited talk by René Guitart at the Séminaire Itinérant des Catégories held in Louvain-la-Neuve to celebrate her 90th birthday ( https://www-lmpa.univ-littoral.fr/~sic/wordpress/?page_id=1609). The slides of René's talk are available here:
https://www-lmpa.univ-littoral.fr/~sic/Louvain2025/Guitart.pdf
On that occasion, she herself participated remotely and presented a talk, in French, about her scientific career:
https://www-lmpa.univ-littoral.fr/~sic/Louvain2025/Ehresmann.pdf
In the final months of her life, Andrée Ehresmann's health declined rapidly. Those who knew her personally appreciated her vision, leadership, generosity, and constant support of younger researchers. With her passing, the category theory community loses a prominent mathematician and a uniquely dedicated figure who contributed greatly to a historic era of French mathematics.
Best regards,
Isar Stubbe, Marino Gran, and René Guitart.
_______________________________________________ Categories mailing list -- categories-list@categories.org.au To unsubscribe send an email to categories-list-leave@categories.org.au
_______________________________________________ Categories mailing list -- categories-list@categories.org.au To unsubscribe send an email to categories-list-leave@categories.org.au
Dear colleagues, As a young researcher myself, I would like to emphasize how supportive Andrée was of the younger generation. I vividly remember the first talk I gave abroad in her presence. It was in Amiens, at the Séminaire Itinérant de Catégories, in January 2020. At the end of my talk, Andrée warmly congratulated me, which felt very encouraging as a second-year PhD student. Later, I remember talking with her over lunch about her memories of the Bourbaki period, the role of her husband in it, and other aspects of that time. Those were history to me, but memories to her. I am deeply saddened by her passing. I would have loved to have had another opportunity to meet her and listen to her. All the best, Corentin Vienne. ________________________________ From: Isar Stubbe via Categories <categories-list@categories.org.au> Sent: Sunday, August 23, 2026 09:54 To: categories-list@categories.org.au <categories-list@categories.org.au> Cc: Isar Stubbe <isar.stubbe@univ-littoral.fr> Subject: [categories] Andrée Ehresmann (1935-2026) Dear Colleagues, With great sadness, we inform you of the passing of Andrée Ehresmann (née Bastiani) on Friday, August 21, 2026, at her home in Amiens. Andrée Ehresmann played a major role in the category theory community for over sixty years. Born in Nice in 1935, she went as a young woman to Paris to study mathematics and Latin. She completed her doctoral thesis, and later her thèse d'État, in functional analysis, under the supervision of Gustave Choquet. From 1967, she was maître de conférences, and then professor, at the Université de Picardie in Amiens. It was Choquet who, already during her doctoral studies, encouraged her to take up category theory in the form that Charles Ehresmann was developing at that time. She later met Charles Ehresmann, who became her husband, and with whom she collaborated intensively until his death in 1979. Together they established the French school in category theory in Amiens, which became a vibrant research center, known internationally. From 1970 onwards, she was the driving force behind the Cahiers de Topologie et Géométrie Différentielle Catégoriques, which she directed until her passing. Andrée Ehresmann worked in various areas of category theory and pioneered the applications of categorical methods to the modeling of living and cognitive systems, mainly in collaboration with Jean-Paul Vanbremeersch. Her fundamental scientific contributions have been presented in an invited talk by René Guitart at the Séminaire Itinérant des Catégories held in Louvain-la-Neuve to celebrate her 90th birthday (https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww-lmpa.univ-littoral.fr%2F~sic%2Fwordpress%2F%3Fpage_id%3D1609&data=05%7C02%7Ccorentin.vienne%40uclouvain.be%7Cdc022c6328eb404445a308df00ffc84d%7C7ab090d4fa2e4ecfbc7c4127b4d582ec%7C1%7C0%7C639230770706547840%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=Ko7BLhMzASDzOCkxIFswzomwsSNrERVEyzH4UGG8q94%3D&reserved=0<https://www-lmpa.univ-littoral.fr/~sic/wordpress/?page_id=1609>). The slides of René's talk are available here: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww-lmpa.univ-littoral.fr%2F~sic%2FLouvain2025%2FGuitart.pdf&data=05%7C02%7Ccorentin.vienne%40uclouvain.be%7Cdc022c6328eb404445a308df00ffc84d%7C7ab090d4fa2e4ecfbc7c4127b4d582ec%7C1%7C0%7C639230770706564635%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=7bc7Ct%2FQwUX5iMeKtCz6b%2F1SYAHTzwH8jm8hVSgAdQM%3D&reserved=0<https://www-lmpa.univ-littoral.fr/~sic/Louvain2025/Guitart.pdf> On that occasion, she herself participated remotely and presented a talk, in French, about her scientific career: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww-lmpa.univ-littoral.fr%2F~sic%2FLouvain2025%2FEhresmann.pdf&data=05%7C02%7Ccorentin.vienne%40uclouvain.be%7Cdc022c6328eb404445a308df00ffc84d%7C7ab090d4fa2e4ecfbc7c4127b4d582ec%7C1%7C0%7C639230770706574999%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=xV3lzPOlNEYG4sdUd82LTA4pqnkSQ49AgSMUi8GjkIQ%3D&reserved=0<https://www-lmpa.univ-littoral.fr/~sic/Louvain2025/Ehresmann.pdf> In the final months of her life, Andrée Ehresmann's health declined rapidly. Those who knew her personally appreciated her vision, leadership, generosity, and constant support of younger researchers. With her passing, the category theory community loses a prominent mathematician and a uniquely dedicated figure who contributed greatly to a historic era of French mathematics. Best regards, Isar Stubbe, Marino Gran, and René Guitart. _______________________________________________ Categories mailing list -- categories-list@categories.org.au To unsubscribe send an email to categories-list-leave@categories.org.au
Dear colleagues, It was pointed out to me by Pierre Agéron that there is non-negligible historical value to archiving the written works (both formal and informal) of a mathematician, and this is clearly the case for Andrée Ehresmann. Is there already a plan to construct such an archive, or does one already exist? I only learned from an interview she gave back in 2013, https://www.youtube.com/watch?v=8u-Wz5LZUOg just how big her influence was on functional analysis before she even encountered category theory. I wish I had met her! As the first- and second- generation of category theorists have been sadly disappearing in recent years, there have been various efforts to preserve some of the history of the subject in their memory. Sometimes this takes the form of a one-off event in celebration and commemoration of the figure in question, sometimes it is an archive of the kind mentioned above. There have also been some interviews and seminars recorded. I wonder if there exists an index of such efforts? Our subject is wide and has a colourful history, with many schisms and international divisions. I like the idea of someone putting together this history some day, and providing that eventual person with historical sources would be very nice. Best regards, Morgan On 23.08.2026 07:54, Isar Stubbe via Categories wrote:
Dear Colleagues,
With great sadness, we inform you of the passing of Andrée Ehresmann (née Bastiani) on Friday, August 21, 2026, at her home in Amiens.
Andrée Ehresmann played a major role in the category theory community for over sixty years.
Born in Nice in 1935, she went as a young woman to Paris to study mathematics and Latin. She completed her doctoral thesis, and later her thèse d'État, in functional analysis, under the supervision of Gustave Choquet. From 1967, she was maître de conférences, and then professor, at the Université de Picardie in Amiens. It was Choquet who, already during her doctoral studies, encouraged her to take up category theory in the form that Charles Ehresmann was developing at that time. She later met Charles Ehresmann, who became her husband, and with whom she collaborated intensively until his death in 1979. Together they established the French school in category theory in Amiens, which became a vibrant research center, known internationally. From 1970 onwards, she was the driving force behind the Cahiers de Topologie et Géométrie Différentielle Catégoriques, which she directed until her passing.
Andrée Ehresmann worked in various areas of category theory and pioneered the applications of categorical methods to the modeling of living and cognitive systems, mainly in collaboration with Jean-Paul Vanbremeersch. Her fundamental scientific contributions have been presented in an invited talk by René Guitart at the Séminaire Itinérant des Catégories held in Louvain-la-Neuve to celebrate her 90th birthday (https://www-lmpa.univ-littoral.fr/~sic/wordpress/?page_id=1609). The slides of René's talk are available here:
https://www-lmpa.univ-littoral.fr/~sic/Louvain2025/Guitart.pdf
On that occasion, she herself participated remotely and presented a talk, in French, about her scientific career:
https://www-lmpa.univ-littoral.fr/~sic/Louvain2025/Ehresmann.pdf
In the final months of her life, Andrée Ehresmann's health declined rapidly. Those who knew her personally appreciated her vision, leadership, generosity, and constant support of younger researchers. With her passing, the category theory community loses a prominent mathematician and a uniquely dedicated figure who contributed greatly to a historic era of French mathematics.
Best regards,
Isar Stubbe, Marino Gran, and René Guitart.
_______________________________________________ Categories mailing list -- categories-list@categories.org.au To unsubscribe send an email to categories-list-leave@categories.org.au
participants (5)
-
Corentin Vienne -
Isar Stubbe -
Jelle Herold -
Morgan Rogers -
Valeria de Paiva